The invention concerns an analytical test element for blood analyses especially by means of a single-use rapid test comprising a substrate body having a preferably microfluidic channel structure for the flow transport of a blood sample from an application site to at least one analytical site. The invention also concerns a corresponding method for carrying out blood analyses in which a blood sample is conveyed by means of a channel structure in an analytical test element from an application site to at least one analytical site.
A test element of this type is known from WO 01/24931. This application describes a channel or flow structure that is specially designed for separating plasma or serum from a whole blood sample and comprises two capillary-active zones where a first zone is composed of a porous matrix material and a second zone which is in contact with the first zone comprises one or more capillary channels. As a result the plasma obtained in the first zone is made available in the second zone free from interfering components as a target fluid for example for glucose tests.
A test element is generally understood as a carrier-bound fluidic (micro)system for receiving a liquid sample which enables sample preparation for an immediate or later analysis independent of a laboratory environment. Such test elements are usually intended to be single-use articles or disposables for near patient diagnostics in which all reagents that are necessary to carry out the test are provided on the carrier or component so that they can also be used by laymen without requiring special handling.
Such test elements are used as test strips especially for blood glucose monitoring by diabetics. On the other hand, the determination of haemoglobin A1c allows a retrospective estimate of the average glucose concentration over the last weeks and thus of the quality of the metabolic control of the diabetic. HbA1c is defined as haemoglobin A that has been glycated with glucose on the N-terminal valine residues of the β chains. HbA1c is usually stated as a percentage of the total haemoglobin which requires a determination of the haemoglobin concentration from the same blood sample in addition to the HbA1c content. This double determination of Hb and HbA1c has previously been carried out on laboratory instruments that are very complicated to operate and are thus error-prone and expensive.